JP2022163421A - ball bearing - Google Patents

Abstract

To provide a rolling bearing which can inhibit a shortage in the amount of oil on a rolling surface to inhibit occurrence of seizure and wear even when rotating at high speed.SOLUTION: A ball bearing includes: an outer ring 21 in which an outside raceway 21a is formed on an inner peripheral surface; an inner ring 22 in which an inside raceway 22a is formed on an outer peripheral surface; a plurality of rolling elements 23 disposed between the outside raceway 21a and the inside raceway 22a; and an annular retainer 25 formed with a plurality of pockets 24 which retain the rolling elements 23 in a rollable manner at intervals in a circumferential direction. A single or a plurality of grooves 24a recessed toward the circumferential direction are formed on at least one side as seen in the circumferential direction of the pocket 24. In a state that the rolling element 23 is retained in the pocket 24, the groove 24a forms a gap between the retainer 25 and the rolling element 23.SELECTED DRAWING: Figure 4

Description

The present invention relates to ball bearings.

In Patent Document 1, a pocket for rollingly holding a rolling element in an annular retainer has a semi-elliptical shape at both ends in the circumferential direction and two circumferential straight lines extending in the circumferential direction. A ball bearing is disclosed that is configured with a circumferential central portion that connects both directional ends. Further, in Patent Document 2, a pair of arc-shaped inner surfaces facing in the circumferential direction and a pair of arc-shaped inner surfaces facing in the axial direction are provided on the inner surface of a pocket that holds rolling elements in an annular retainer so as to be able to roll. A ball bearing is disclosed that is provided with four radial grooves that divide into four.

JP 2011-185315 A JP 2009-14205 A

In the ball bearing disclosed in Patent Document 1, the pocket of the retainer has a non-circular shape, and the both ends in the circumferential direction are semi-elliptical in order to reduce the contact surface pressure during rotation of the bearing. Therefore, when the bearing rotates, the retainer and the rolling elements come into contact with each other at both ends in the circumferential direction of the semi-elliptical shape, and the oil on the surfaces of the rolling elements is scraped off by the retainer due to the rotation of the rolling elements. In the ball bearing disclosed in Patent Document 2, although radial grooves are formed in the pockets of the retainer, the rolling elements come into contact with the circumferential ends of the arc-shaped pockets during rotation of the bearing. Therefore, the oil on the surfaces of the rolling elements is scraped off by the retainer due to the rotation of the rolling elements. Furthermore, if the ball bearing rotates at a high speed, the amount of oil flowing into the rolling surfaces where the rolling elements roll and come into contact with the raceway surfaces of the outer ring and the inner ring becomes extremely small. there is a possibility.

Therefore, we created a tester that can visualize the state of lubrication inside a ball bearing that rotates at high speed, and observed the state of lubrication inside the ball bearing when rotating a conventional ball bearing at high speed. The ball bearing 1 used in the evaluation test has a shape corresponding to type 6808, and is a visualization bearing in which only the outer ring 2 is made of quartz. The overall structure of the ball bearing 1 is shown in FIGS. 9 and 10. FIG. As shown in FIGS. 9 and 10, the ball bearing 1 includes an outer ring 2 made of transparent quartz, an inner ring 3 made of steel, steel balls 4 as rolling elements, and the steel balls 4 spaced apart in the circumferential direction. and a retainer 5 that holds it so that it can roll.

The shape of the retainer 5 is shown in FIGS. 11, 12 and 13. FIG. In order to clearly show the shape of the cage 5, FIG. 12 shows the cross section of only the cage 5 and the steel balls 4. As shown in FIG. The retainer 5 has a pocket 6 formed on one side in the axial direction for holding the steel ball 4 in a rollable manner, and the pocket 6 is open on one side. A side surface 7 on the other side in the axial direction of the retainer 5 is flat. In addition, an oil passage hole penetrating in the axial direction is not formed in the side surface 7 of the retainer.

FIG. 14 shows an outline of the testing machine used for the evaluation test. A horizontally extending rotary shaft 8 is rotatably supported by two shaft support bearings 9 and rotated by a motor 10 . The rotating shaft 8 is inserted and fixed inside the inner ring 3 of the ball bearing 1 , and the inner ring 3 rotates together with the rotating shaft 8 . The outer ring 2 of the ball bearing 1 is fixed inside the housing 11 . A camera 12 is arranged above the ball bearing 1, and an observation hole 13 is formed in the housing 11 above the ball bearing 1, so that the camera 12 can photograph the top of the outer ring 2 from above. .

An oil supply nozzle 14 supplies oil between the top portion of the outer ring 2 and the inner ring 3, and the oil accumulated in the housing 11 below the ball bearing 1 is recovered by an oil pump 15 and circulated. Toyota Auto Fluid WS, which is commercially available ATF (Automatic Transmission Fluid), mixed with coumarin-6, which is a fluorescent agent, was used as the oil, and the oil amount distribution was observed by a fluorescence method. An LED flash illumination with a wavelength of 405 nm was used as excitation light.

15 is a top view of the ball bearing 1. FIG. Since the outer ring 2 is made of transparent quartz, when the ball bearing 1 is viewed from above, the raceway surface 3a of the inner ring 3 and the positions of the steel balls 4 can also be confirmed. An area surrounded by a dashed line in FIG. 13 is an observation area of the camera 12. In FIG. The observation area has a field of view of 23.6 mm×17.7 mm. The oil distribution inside the rotating ball bearing 1 was observed by setting the time per light emission of the LED flash illumination to 3 μsec and irradiating the light emission in accordance with the frame note of 40 fps of the camera 12 . The amount of oil supplied to the ball bearing 1 was constant at 100 ml/min, the radial load applied to the ball bearing 1 from above was also constant at 300 N, and the shaft rotation speed was changed between about 2000 rpm and about 20000 rpm for observation.

16 and 17 schematically show the observation results of the oil amount distribution around the rolling surface. FIG. 16 shows the observation results when the shaft rotation speed is about 2000 rpm (strictly 1910 rpm), and FIG. 17 shows the observation results when the shaft rotation speed is about 20000 rpm (strictly 20200 rpm). 16 and 17, the positions of the steel balls 4 are indicated by solid lines, the center lines of the steel balls 4 by one-dot chain lines, and the positions of the retainer 5 by two-dot chain lines. The steel ball 4 revolves toward the right side in FIGS. 16 and 17. FIG. The refueling nozzle 14 is also depicted in FIGS. 16 and 17 . In FIGS. 16 and 17, areas where a large amount of oil is present are shown in darker gray, and white areas indicate that almost no oil was present.

As shown in FIG. 16, under low rotation conditions where the shaft rotation speed is about 2000 rpm, oil was generally filled except for the vicinity of the outlet side of the steel balls 4 (the left side of the steel balls 4 in FIG. 14). On the exit side of the steel ball 4, there is a region where the oil is scarce.

As shown in FIG. 17, under high rotation conditions of about 20,000 rpm, the revolution raceway of the steel balls 4 and the cage 5 is not filled with oil, and the oil is not filled with oil on the outside of the revolution raceway in the axial direction. distributed near the boundary. This is because, at high speeds, the speed at which the oil is removed due to the revolution of the steel balls 4 and the rotation of the cage 5 is excessively increased relative to the inflow speed of the oil, and the increase in the revolution speed of the steel balls 4 , and the expansion of the cavitation region on the exit side of the steel ball 4 (left side of the steel ball 4 in FIG. 17). On the inlet side of the steel ball 4 (on the right side of the steel ball 4 in FIG. 17), there was a triangular portion with a large amount of oil. It is considered that this is because the oil is supplied from the inner ring 3 side to the opening of the U-shaped pocket 6 of the retainer 5 . However, in any case, compared to the low speed condition, the oil at the inlet side of the steel ball 4 and the top portion of the steel ball 4, which is the rolling surface with the outer ring 2, is less under the high speed condition. It is determined that there is an oil shortage. From the viewpoint of friction torque reduction, the smaller the amount of oil on the rolling contact surface, the better.

Thus, as a result of observing the oil amount distribution inside the ball bearing 1, during high-speed rotation, the oil is pushed aside by the steel balls 4 and the cage 5 rotating at high speed, and the amount of oil flowing into the orbital portion thereof is small. It turned out to be very few. In this case, even if seizure and wear can be suppressed by improving the oil retention property according to the measures disclosed in Patent Document 1 in short-time use, seizure and wear will occur in long-term use conditions because the oil will eventually be depleted. is considered to be uncontrollable. Therefore, in order to suppress seizure and wear of a ball bearing rotating at high speed over a long period of time, it is necessary to promote the inflow of oil to the inlet side of the steel balls 4 .

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide a ball bearing capable of suppressing insufficient amount of oil on the rolling surface and suppressing the occurrence of seizure and wear even when rotating at high speed.

A ball bearing according to the present invention comprises an outer ring having an outer raceway formed on its inner peripheral surface, an inner ring having an inner raceway formed on its outer peripheral surface, and rolling elements arranged between the outer raceway and the inner raceway. and an annular retainer formed with a plurality of pockets for rotatably retaining the rolling elements spaced apart in the circumferential direction, wherein the outer ring and the inner ring rotate relative to each other about a central axis. A possible ball bearing, wherein at least one side of the pocket in the circumferential direction is formed with one or more grooves recessed in the circumferential direction to retain the rolling elements in the pocket. , a gap is provided between the retainer and the rolling element by the groove.

According to the present invention, grooves recessed in the circumferential direction are formed on at least one side of the pocket in the circumferential direction. It can reach the contact point between the outer ring or inner ring on the opposite side in the radial direction and the rolling ball through the groove without being scraped off by the vessel, so even if it rotates at high speed, there is no shortage of oil on the rolling surface. It is possible to provide a rolling bearing that can suppress the occurrence of seizure and wear.

In one aspect of the ball bearing according to the present invention, the range in which the groove is provided along the direction of the central axis is either the width of the outer raceway or the width of the inner raceway along the direction of the central axis. It may be equal to or greater than the width of the wider one.

According to this aspect, the oil on the surfaces of the rolling elements is not scraped off by the cage due to the rotation of the rolling elements, but passes through the grooves and reaches the contact points between the outer ring or the inner ring on the opposite side in the radial direction and the rolling balls. Therefore, even if the roller rotates at high speed, it is possible to suppress the shortage of oil on the rolling contact surfaces, thereby suppressing the occurrence of seizure and wear.

In one aspect of the ball bearing according to the present invention, the pocket may be provided with a rolling element holding portion having a surface shape corresponding to the surface shape of the rolling element.

According to this aspect, by providing the rolling element holding portion, it is possible to suppress the shortage of the amount of oil on the rolling surface and suppress the occurrence of seizure and wear while the pocket reliably holds the rolling ball.

In one aspect of the ball bearing according to the present invention, the width of the rolling element holding portion in the direction of the central axis may be 1 mm or more.

According to this aspect, by setting the axial width of the rolling element holding portion to an appropriate value, the pocket can reliably hold the rolling ball.

In one aspect of the ball bearing according to the present invention, a plurality of the grooves are formed, and the interval between the grooves adjacent in the direction of the central axis is such that the rolling elements contact the outer raceway or the inner raceway. The width of the top of the groove in the direction of the central axis may be 0.25 times or less than the major axis of the contact ellipse.

According to this aspect, by setting the width of the groove in the axial direction and the interval between the grooves to appropriate values, the oil can easily pass between the cage and the rolling balls. , it is possible to suppress the shortage of the amount of oil on the rolling surface, and suppress the occurrence of seizure and wear.

In one aspect of the ball bearing according to the present invention, the depth of the groove in the circumferential direction is either the contact depth indicating the amount of elastic deformation between the rolling element and the pocket, or the arithmetic mean roughness of the inner surface of the pocket. It may be 5 times or more the larger one and 0.25 times or less of the distance between the circumferentially adjacent pockets.

According to this aspect, by setting the depth of the groove to an appropriate value, the oil can easily pass between the retainer and the rolling balls, so that the pockets can reliably hold the rolling balls. .

INDUSTRIAL APPLICABILITY The present invention can provide a rolling bearing capable of suppressing insufficient amount of oil on the rolling surface and suppressing the occurrence of seizure and wear even when rotating at high speed.

It is the figure which expanded and showed a part of side surface of the ball bearing of 1st Embodiment. FIG. 2 is a cross-sectional view taken along line DD in FIG. 1; It is a figure which shows the shape which looked at the area|region drawn in FIG. 1 of the retainer from the radial outside. FIG. 4 is a drawing in which rolling elements are added to FIG. 3, and a cross-sectional view taken along line EE in the drawing. FIG. 5 is a cross-sectional view taken along line FF in FIG. 4; FIG. 4 is a diagram showing elastic deformation due to contact between rolling elements and a retainer; FIG. 2 is a view showing the shape of the retainer of the ball bearing of the second embodiment of the area depicted in FIG. 1 as viewed from the outside in the radial direction, and a cross-sectional view taken along the line GG in the figure. FIG. 5 is a diagram showing the shape of grooves when axially adjacent grooves are connected at the radial end of the retainer; FIG. 3 is a side view of a ball bearing used in an evaluation test for observing the internal lubrication state; FIG. 10 is a cross-sectional view taken along the line AA in FIG. 9; It is the figure which expanded and showed a part of side surface of the ball bearing used for the evaluation test. FIG. 12 is a diagram showing a cross section of the retainer taken along the line BB in FIG. 11; FIG. 12 is a sectional view taken along line CC in FIG. 11; It is a figure which shows the outline of the testing machine used for the evaluation test which observes the lubricating state inside a ball bearing. It is a figure which shows the observation area|region in the evaluation test which observes the lubricating state inside a ball bearing. FIG. 5 is a diagram schematically showing observation results of the oil amount distribution around the rolling surface when the shaft rotation speed is about 2000 rpm. FIG. 4 is a diagram schematically showing observation results of the oil amount distribution around the rolling surface when the shaft rotation speed is about 20000 rpm.

<First Embodiment>
The ball bearing 20 of the first embodiment will be described below with reference to the drawings. FIG. 1 is an enlarged view showing a part of the side surface of the ball bearing 20, and FIG. 2 is a sectional view taken along line DD in FIG. As shown in FIGS. 1 and 2, the ball bearing 20 includes an outer ring 21, an inner ring 22, rolling elements 23 and a retainer 25. As shown in FIG. The outer ring 21 and the inner ring 22 are annular members. An outer raceway 21 a is formed on the inner peripheral surface of the outer ring 21 so as to follow the surfaces of the rolling elements 23 . An inner raceway 22 a is formed on the outer peripheral surface of the inner ring 22 so as to follow the surfaces of the rolling elements 23 . The outer raceway 21a of the outer ring 21 and the inner raceway 22a of the inner ring 22 are provided at predetermined intervals along the circumferential direction of the annular ball bearing 20 . The rolling elements 23 are held in a space formed by the outer raceway 21a of the outer ring 21 and the inner raceway 22a of the inner ring 22 in a rollable state. Moreover, the retainer 25 is arranged between the outer ring 21 and the inner ring 22, and retains the plurality of rolling elements 23 at predetermined intervals in the circumferential direction so that they can roll. In the ball bearing 20, the rolling elements 23 roll between the outer ring 21 and the inner ring 22, so that the outer ring 21 and the inner ring 22 rotate with the central axes of the outer ring 21 and the inner ring 22 as rotation axes (hereinafter simply referred to as axes). are relatively rotatable.

FIG. 3 shows the shape of the area of the retainer 25 depicted in FIG. 1 viewed from the outside in the radial direction. As shown in FIG. 3, the retainer 25 is formed with pockets 24 that hold the rolling elements 23 so that they can roll. On one side in the axial direction of the pocket 24 , a rolling element holding portion 24 b having an inner surface of a spherical shape corresponding to the surface of the rolling element 23 and having a structure to fit the rolling element 23 is provided. On the other side in the axial direction of the pocket 24, a pawl-shaped rolling element holding portion 24c having a spherical inner surface corresponding to the surface of the rolling element 23 and having a fitting structure for the rolling element 23 is provided.

Grooves 24a recessed in the circumferential direction are formed on both sides of the pocket 24 in the circumferential direction. The groove 24a penetrates the retainer 25 in the radial direction of the retainer 25 .

In FIG. 4, the drawing with the rolling element 23 added to FIG. FIG. 5 is a view showing a cross section taken along the line FF in the left drawing of FIG. As shown in FIG. 4, when the rolling elements 23 are held in the pockets 24 of the cage 25, a gap of depth D1 is provided between the rolling elements 23 and the cage 25 by the grooves 24a. A contact ellipse 23a hatched in FIG. 4 indicates a region where the rolling element 23 contacts the outer raceway 21a and the inner raceway 22a. In the diagram on the right side of FIG. 4, the portion corresponding to the contact ellipse 23a is drawn with a thick solid line.

As shown in FIG. 5, for example, when the outer ring 21 is fixed and the inner ring 22 is rotated clockwise as indicated by arrow A1, the rolling elements 23 in sliding contact with the inner ring 22 move as indicated by arrow A2. While rotating counterclockwise, it revolves clockwise as indicated by arrow A3. Since the grooves 24a are formed in the pockets 24, the oil swirled up from the contact points between the outer ring 21 and the rolling elements 23 onto the surface of the rolling elements 23 is not scraped off by the edge of the retainer 25, etc., and is shown by the arrow A4. As shown, it is possible to reach the point of contact between the inner ring 22 and the rolling element 23 on the diametrically opposite side through the groove 24a. Similarly, the oil that is swirled up onto the surface of the rolling element 23 from the contact point between the inner ring 22 and the rolling element 23 is not scraped off by the edge of the retainer 25, and flows through the groove 24a as indicated by arrow A5. The contact point between the outer ring 21 and the rolling element 23 on the opposite side in the radial direction can be reached. Therefore, even if the ball bearing 20 rotates at a high speed, it is possible to suppress the shortage of the amount of oil on the rolling contact surface, thereby suppressing the occurrence of seizure and wear.

In the ball bearing 20 according to the present embodiment, the grooves 24a are provided on both circumferential sides of the pocket 24 of the retainer 25, but a certain effect can be obtained by providing the grooves 24a on either side. be able to.

Here, it is preferable that the range W1 in which the groove 24a is provided along the axial direction of the ball bearing 20 is equal to or larger than the width W2 of the outer raceway 21a provided in the outer ring 21 . Also, the range W1 of the groove 24a along the axial direction of the ball bearing 20 is preferably equal to or greater than the width W3 of the inner raceway 22a provided in the inner ring 22. As shown in FIG. That is, it is preferable that the range W1 of the groove 24a is equal to or greater than the wider one of the width W2 of the outer raceway 21a and the width W3 of the inner raceway 22a. As a result, in the trajectory from the outer ring 21 to the inner ring 22 indicated by arrow A4 in FIG. It can effectively pass through the groove 24a without being scraped off by the edge of the groove 24a. However, in order to increase the mechanical strength of the retainer 25 and the ability of the retainer 25 to retain the rolling elements 23, the range W1 of the grooves 24a is made substantially equal to the width W2 of the outer raceway 21a and the width W3 of the inner raceway 22a. is preferred.

FIG. 6 shows elastic deformation due to contact between the rolling elements 23 and the retainer 25 . The positions of the rolling elements 23 before elastic deformation are indicated by dashed lines, and the positions of the rolling elements 23 after elastic deformation are indicated by solid lines. As shown in FIG. 6, when the outer ring 21 or the inner ring 22 of the ball bearing 20 is rotated to cause the rolling elements 23 to revolve toward the right side of FIG. )d occur in the circumferential direction. Here, as shown in FIG. 6, the distance between circumferentially adjacent pockets 24 is defined as D2. The depth D1 of the groove 24a shown in FIG. 4 is preferably 0.25 times or less the distance D2 between the pockets 24 adjacent in the circumferential direction. The depth D1 of the groove 24a is preferably five times or more the arithmetic mean roughness of the inner surface of the pocket 24 or the amount of elastic deformation d, whichever is larger.

Further, it is preferable that the axial width D3 of the rolling element holding portion 24b forming the pocket 24 for holding the rolling element 23 in the retainer 25 is 1 mm or more. Further, it is preferable that the axial width D4 of the rolling element holding portion 24c forming the pocket 24 for holding the rolling element 23 in the retainer 25 is 1 mm or more. By setting the axial width D3 of the rolling element holding portion 24b and the axial width D4 of the rolling element holding portion 24c to 1 mm or more, the rolling elements 23 can be reliably held by the pockets 24 of the retainer 25. can be done.

<Second embodiment>
Next, the ball bearing 30 of 2nd Embodiment is demonstrated, referring drawings. The ball bearing 30 has the same configuration as the ball bearing 20 of the first embodiment, except that a plurality of grooves 34a are formed on both circumferential sides of the pocket 34 of the retainer 35. . Therefore, the same reference numerals are given to the same configurations as those of the ball bearing 20 of the first embodiment, and the description thereof is omitted.

7 shows on the left a diagram showing the shape of the area of the retainer 35 of the ball bearing 30 drawn in FIG. ing. As shown in FIG. 7, the retainer 35 is formed with pockets 34 that hold the rolling elements 23 in a rollable manner. On one side in the axial direction of the pocket 34, a rolling element holding portion 24b having a spherical inner surface corresponding to the surface of the rolling element 23 and having a structure to fit the rolling element 23 is provided. On the other side of the pocket 34 in the axial direction, a pawl-shaped rolling element holding portion 24 c having a spherical inner surface corresponding to the surface of the rolling element 23 and having a structure to fit the rolling element 23 is provided.

A plurality of grooves 34a recessed in the circumferential direction are formed on both sides of the pocket 34 in the circumferential direction. This embodiment shows an example in which five grooves 34a are formed in each groove. All of the grooves 34a penetrate the retainer 35 in the radial direction of the retainer 35 .

By providing the grooves 34a in the pockets 34, the oil that is swirled up on the surfaces of the rolling elements 23 from the contact points between the outer ring 21 and the rolling elements 23 is not scraped off by the retainer 35 at the portions where the grooves 34a are provided. , through the groove 34a to the point of contact between the inner ring 22 and the rolling element 23 on the opposite side in the radial direction. Similarly, the oil that is swirled up on the surface of the rolling element 23 from the contact point between the inner ring 22 and the rolling element 23 is not scraped off by the retainer 35 in the portion where the groove 34a is provided, and passes through the groove 34a to the diameter of the rolling element 23. The contact point between the outer ring 21 and the rolling element 23 on the opposite side can be reached. Therefore, even if the ball bearing 30 rotates at a high speed, it is possible to suppress the shortage of the amount of oil on the rolling contact surface, thereby suppressing the occurrence of seizure and wear.

In the ball bearing 30 of the present embodiment, the grooves 34a are provided on both circumferential sides of the pocket 34 of the retainer 35. However, a certain effect can be obtained by providing the grooves 34a on either one of the pockets 34. be able to.

A range W4 in which the groove 34a is provided along the axial direction of the ball bearing 30 is preferably equal to or larger than the width W5 of the outer raceway 21a provided in the outer ring 21. As shown in FIG. Also, the range W4 of the groove 34a along the axial direction of the ball bearing 30 is preferably equal to or greater than the width W6 of the inner raceway 22a provided in the inner ring 22. As shown in FIG. The shape of the grooves 34a is not limited to the shape shown in FIG. 7. As shown in FIG.

The interval I between the axially adjacent grooves 34a is preferably 0.5 times or less the major axis S of the contact ellipse 23a shown in FIG. Also, the axial width D5 of the top of the groove 34a is preferably 0.25 times or less the major axis S of the contact ellipse 23a.

Also in the ball bearing 30, as in the ball bearing 20 of the first embodiment, the depth D6 of the groove 34a is five times the arithmetic mean roughness of the inner surface of the pocket 24 or the amount of elastic deformation d, whichever is larger. It is preferable that the distance is equal to or less than 0.25 times the distance D2 shown in FIG. Further, in the ball bearing 30 as well, the axial width D7 of the rolling element holding portion 24b and the axial width D8 of the rolling element holding portion 24c are both preferably 1 mm or more.

REFERENCE SIGNS LIST 1 ball bearing 2 outer ring 3 inner ring 3a raceway surface 4 steel ball 5 retainer 6 pocket 7 side surface 8 rotating shaft 9 shaft support bearing 10 motor 11 housing 12 camera 13 observation hole , 14 lubrication nozzle, 15 oil pump, 20, 30 ball bearing, 21 outer ring, 21a outer raceway, 22 inner ring, 22a inner raceway, 23 rolling element, 23a contact ellipse, 24, 34 pocket, 24a, 34a groove, 24b, 24c Rolling element holding part, 25, 35 Cage.

Claims (6)

An outer ring having an outer raceway formed on its inner peripheral surface, an inner ring having an inner raceway formed on its outer peripheral surface, rolling elements disposed between the outer raceway and the inner raceway, and the rolling elements arranged in the circumferential direction an annular retainer having a plurality of pockets that are rotatably held at intervals, wherein the outer ring and the inner ring are relatively rotatable about a central axis,
A single or a plurality of grooves recessed in the circumferential direction are formed on at least one side of the pocket in the circumferential direction,
A ball bearing, wherein a gap is provided between the retainer and the rolling elements by the grooves in a state where the rolling elements are held in the pockets. A ball bearing according to claim 1,
The range in which the groove is provided along the direction of the central axis is equal to or larger than the wider one of the width of the outer raceway and the width of the inner raceway along the direction of the central axis. ball bearings. The ball bearing according to claim 1 or 2,
A ball bearing, wherein the pocket is provided with a rolling element holding portion having a surface shape corresponding to the surface shape of the rolling element. A ball bearing according to claim 3,
A ball bearing, wherein the rolling element holding portion has a width of 1 mm or more in the direction of the central axis. The ball bearing according to any one of claims 1 to 4,
A plurality of the grooves are formed,
The interval between the grooves adjacent in the direction of the central axis is 0.5 times or less the major axis of the contact ellipse where the rolling element contacts the outer raceway or the inner raceway,
A ball bearing, wherein the width of the top of the groove in the direction of the central axis is 0.25 times or less the major axis. The ball bearing according to any one of claims 1 to 5,
The depth of the groove in the circumferential direction is at least five times the larger one of the contact depth indicating the amount of elastic deformation between the rolling element and the pocket or the arithmetic mean roughness of the inner surface of the pocket, A ball bearing, wherein the distance between the pockets adjacent to each other in the circumferential direction is 0.25 times or less.

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